add string verifying w/ regex

go.mod

@@ -2,9 +2,14 @@ module unpackstring
 
 go 1.19
 
-require github.com/stretchr/testify v1.7.0
+require (
+	github.com/gijsbers/go-pcre v0.0.0-20161214203829-a84f3096ab3c
+	github.com/stretchr/testify v1.7.0
+)
 
 require (
+	github.com/GRbit/go-pcre v1.0.1 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

@@ -1,6 +1,10 @@
+github.com/GRbit/go-pcre v1.0.1 h1:8F7Wj1rxIq8ejKSXVVW2wE+4I4VnZbuOemrMk8kn3hc=
+github.com/GRbit/go-pcre v1.0.1/go.mod h1:0g7qVGbMpd2Odevd92x1RpaLpR3c3F/Gv2HEnI7CwEA=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gijsbers/go-pcre v0.0.0-20161214203829-a84f3096ab3c h1:o5z/Stj4aWUiDiCVFdEOgXcwNF+Z7mQSlvDTaWBK98Q=
+github.com/gijsbers/go-pcre v0.0.0-20161214203829-a84f3096ab3c/go.mod h1:Bd83Kcti1U5OMXYYTjilhd6os+l6AmlTMVbDtaBvycQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

unpack.go

@@ -2,12 +2,21 @@ package unpackstring
 
 import (
 	"errors"
+	"github.com/GRbit/go-pcre"
 )
 
 var ErrInvalidString = errors.New("invalid string")
 
-func Unpack(_ string) (string, error) {
+func Unpack(str string) (string, error) {
 	// Place your code here.
-	// test
+
+	re, _ := pcre.Compile(`^\d|\d{2,}|\\(?=\D)|(?=\\)`, pcre.UTF8)
+
+	res := re.MatchStringWFlags(str, pcre.UTF8)
+
+	if res == true {
+		return "", ErrInvalidString
+	}
+
 	return "", nil
 }